Apple has released macOS 10.14.5, iOS 12.3, tvOS 12.3, and watchOS 5.2.1. macOS 10.14.5 contains security and bug fixes. To download it, go to the Settings app and click Software Update.
iOS 12.3 and tvOS 12.3 add support for the new Apple TV app. The former is available on eligible iPhone and iPads in the Settings app (Settings —> General —> Software Update). iOS 12.3 also offers tweaks to the Wallet app. You can initiate the tvOS 12.1.1 update via the Settings menu on the Apple TV.
watchOS 5.2.1 is a maintenance release with bug fixes and other improvements. You can install it via the Apple Watch app on your iPhone. The update requires that your Apple Watch is connected to its charger, charged to at least 50%, and in range of your Wi-Fi connected iPhone.